As an aerial imaging display device which projects floating images in air, a structure comprising a retroreflective member has been proposed. For example, a structure comprising a polarizing filter which transmits polarized components parallel to a transmission axis and reflects polarized components perpendicular to the transmission axis, and a structure comprising a half mirror are studied. The former requires optical films such as a polarizing filter and a retardation film, whereas the latter entails a possible drawback that external light may enter the display device to reduce contrast.